/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_max_q7.c
 * Description:  Maximum value of a Q7 vector
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupStats
 */

/**
  @addtogroup Max
  @{
 */

/**
  @brief         Maximum value of a Q7 vector.
  @param[in]     pSrc       points to the input vector
  @param[in]     blockSize  number of samples in input vector
  @param[out]    pResult    maximum value returned here
  @param[out]    pIndex     index of maximum value returned here
  @return        none
 */
#if defined(ARM_MATH_MVEI)

#include "arm_helium_utils.h"

static void arm_small_blk_max_q7(
	const q7_t *pSrc,
	uint8_t blockSize,
	q7_t *pResult,
	uint32_t *pIndex)
{
	uint32_t        blkCnt;           /* loop counters */
	q7x16_t         vecSrc;
	q7x16_t         curExtremValVec = vdupq_n_s8(Q7_MIN);
	q7_t            maxValue = Q7_MIN, temp;
	uint32_t        idx = blockSize;
	uint8x16_t      indexVec;
	uint8x16_t      curExtremIdxVec;
	mve_pred16_t    p0;


	indexVec = vidupq_u8((uint32_t)0, 1);
	curExtremIdxVec = vdupq_n_u8(0);

	blkCnt = blockSize >> 4;
	while (blkCnt > 0U) {
		vecSrc = vldrbq_s8(pSrc);
		pSrc += 16;
		/*
		 * Get current max per lane and current index per lane
		 * when a max is selected
		 */
		p0 = vcmpgeq(vecSrc, curExtremValVec);
		curExtremValVec = vpselq(vecSrc, curExtremValVec, p0);
		curExtremIdxVec = vpselq(indexVec, curExtremIdxVec, p0);

		indexVec = indexVec +  16;
		/*
		 * Decrement the blockSize loop counter
		 */
		blkCnt--;
	}


	/*
	 * Get max value across the vector
	 */
	maxValue = vmaxvq(maxValue, curExtremValVec);
	/*
	 * set index for lower values to max possible index
	 */
	p0 = vcmpgeq(curExtremValVec, maxValue);
	indexVec = vpselq(curExtremIdxVec, vdupq_n_u8(blockSize), p0);
	/*
	 * Get min index which is thus for a max value
	 */
	idx = vminvq(idx, indexVec);

	/*
	 * tail
	 */
	blkCnt = blockSize & 0xF;

	while (blkCnt > 0U) {
		/* Initialize temp to the next consecutive values one by one */
		temp = *pSrc++;

		/* compare for the maximum value */
		if (maxValue < temp) {
			/* Update the maximum value and it's index */
			maxValue = temp;
			idx = blockSize - blkCnt;
		}

		/* Decrement loop counter */
		blkCnt--;
	}
	/*
	 * Save result
	 */
	*pIndex = idx;
	*pResult = maxValue;
}

void arm_max_q7(
	const q7_t *pSrc,
	uint32_t blockSize,
	q7_t *pResult,
	uint32_t *pIndex)
{
	int32_t   totalSize = blockSize;

	if (totalSize <= UINT8_MAX) {
		arm_small_blk_max_q7(pSrc, blockSize, pResult, pIndex);
	} else {
		uint32_t  curIdx = 0;
		q7_t      curBlkExtr = Q7_MIN;
		uint32_t  curBlkPos = 0;
		uint32_t  curBlkIdx = 0;
		/*
		 * process blocks of 255 elts
		 */
		while (totalSize >= UINT8_MAX) {
			const q7_t     *curSrc = pSrc;

			arm_small_blk_max_q7(curSrc, UINT8_MAX, pResult, pIndex);
			if (*pResult > curBlkExtr) {
				/*
				 * update partial extrema
				 */
				curBlkExtr = *pResult;
				curBlkPos = *pIndex;
				curBlkIdx = curIdx;
			}
			curIdx++;
			pSrc += UINT8_MAX;
			totalSize -= UINT8_MAX;
		}
		/*
		 * remainder
		 */
		arm_small_blk_max_q7(pSrc, totalSize, pResult, pIndex);
		if (*pResult > curBlkExtr) {
			curBlkExtr = *pResult;
			curBlkPos = *pIndex;
			curBlkIdx = curIdx;
		}
		*pIndex = curBlkIdx * UINT8_MAX + curBlkPos;
		*pResult = curBlkExtr;
	}
}
#else
void arm_max_q7(
	const q7_t *pSrc,
	uint32_t blockSize,
	q7_t *pResult,
	uint32_t *pIndex)
{
	q7_t maxVal, out;                              /* Temporary variables to store the output value. */
	uint32_t blkCnt, outIndex;                     /* Loop counter */

#if defined (ARM_MATH_LOOPUNROLL)
	uint32_t index;                                /* index of maximum value */
#endif

	/* Initialise index value to zero. */
	outIndex = 0U;
	/* Load first input value that act as reference value for comparision */
	out = *pSrc++;

#if defined (ARM_MATH_LOOPUNROLL)
	/* Initialise index of maximum value. */
	index = 0U;

	/* Loop unrolling: Compute 4 outputs at a time */
	blkCnt = (blockSize - 1U) >> 2U;

	while (blkCnt > 0U) {
		/* Initialize maxVal to next consecutive values one by one */
		maxVal = *pSrc++;

		/* compare for the maximum value */
		if (out < maxVal) {
			/* Update the maximum value and it's index */
			out = maxVal;
			outIndex = index + 1U;
		}

		maxVal = *pSrc++;
		if (out < maxVal) {
			out = maxVal;
			outIndex = index + 2U;
		}

		maxVal = *pSrc++;
		if (out < maxVal) {
			out = maxVal;
			outIndex = index + 3U;
		}

		maxVal = *pSrc++;
		if (out < maxVal) {
			out = maxVal;
			outIndex = index + 4U;
		}

		index += 4U;

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Loop unrolling: Compute remaining outputs */
	blkCnt = (blockSize - 1U) % 4U;

#else

	/* Initialize blkCnt with number of samples */
	blkCnt = (blockSize - 1U);

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

	while (blkCnt > 0U) {
		/* Initialize maxVal to the next consecutive values one by one */
		maxVal = *pSrc++;

		/* compare for the maximum value */
		if (out < maxVal) {
			/* Update the maximum value and it's index */
			out = maxVal;
			outIndex = blockSize - blkCnt;
		}

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Store the maximum value and it's index into destination pointers */
	*pResult = out;
	*pIndex = outIndex;
}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of Max group
 */
